On Friday evening, the U.S. Forest Service said flames were 55 percent contained and 174 acres of land were still burning.

No structures have been threatened and no injuries were reported.

The fire began at 1 p.m. Wednesday and firefighters were unsure what ignited it. More than 100 people camping near Tassajara Hot Springs were evacuated Wednesday afternoon.

Because the wildfire is burning on steep, rugged, and inaccessible terrain, air tankers and helicopters were called in from Hollister and King City for an air attack, Andrew Madsen of the U.S. Forest Service said.

Madsen said cool weather worked in firefighters' favor as wind speeds dropped and heavy fog hung over the sky.

Flames blistered land that was already burned in the 2008 West Basin Fire. The wildfire is located northeast from Julia Pfeiffer Burns State Park, northwest from the Arroyo Seco Campground, and about 1 mile from Tassajara Springs.